Industries that package their products in can or bottle-type containers are constantly searching for ways to maximize production output. With the ever-increasing demand for higher production rates, surface conveyor systems have been designed which are capable of accumulating a large number of containers so that the surface conveyor can accommodate a varying backlog of the containers. For example, the infeed of the conveyor system might be several times wider than the containers so as to be able to receive the containers in random multiple width arrangements of containers. Usually, the wider the infeed conveyor, the greater its accumulation capability will be. Hence, several container-dependent industries now use relatively wide conveyor systems.
Although wider conveyor systems have helped to increase production rates, production rates still are limited because the typical production line requires that containers be fed into a subsequent work station in a single file moved along a conveyor line. For example, standard equipment such as inspection lights and/or electronic bottle inspectors, product fillers, container cappers or sealers, container de-cappers, and labelers all require that the containers must enter in a single file. In order to narrow the container stream width from an initial multiple width of containers to single file, combiners have been developed. The smooth transfer of containers from a wide conveyor surface to single file width makes the combiner one of today's more important items in bottling production lines. Similarly, once the containers have been combined, they must be moved as quickly and as efficiently as possible from the combiner to, and between, subsequent workstations.
In the past, multiple flat top chain conveyors and converging rails have been used in order to combine containers from a mass of containers into a single file or row of containers. When combining lightweight containers the problem arises in that the side-to-side compaction of the containers against one another causes some of the containers to be lifted above the conveyor belt sorter by adjacent bottles and to thus lose speed because the lifted bottles no longer ride on the conveyor chain. This side-to-side compaction also creates a problem where the containers bridge against and between the side rail guides of the combiner so that the movement of the containers stalls while following containers push the containers next ahead, which tends to cause more bridging between the side rails instead of pulling the containers in spaced relationship into single file.
Also, in the past it was generally believed in the industry that glass bottle combiners must be designed to satisfy the following conditions: (1) the combiner must be at least two meters long; (2) the downstream end of the combiner must be located at least two meters upstream from the equipment it feeds; (3) the combiner must use tapered guide rails; (4) the combiner should use two chains--a 71/2 inch width feed chain and a 31/4 inch width single discharge conveyor chain; (5) the relation of the infeed chain speed to the discharge chain speed must be 66%; and (6) the combiner must always be full of bottles to maintain the bottle position that produces smooth flow. A combiner made within these six specifications typically yields an output of 600 to 1000 bottles per minute ("bpm") using standard 12 oz. glass bottles; 1500 cans per minute; and no more than 600 bpm for standard 12 oz. plastic bottles. Twelve ounce plastic bottles are limited to 600 bpm due to their light weight, low bottle stability, high bottle compressibility, and the high degree of friction that exists between the plastic bottles and the guide rails.
If the above six combiner specifications are used with an air-jet guide rail to combine lightweight containers, such as 12 oz. plastic bottles, combiner rates of 650 bpm have been achieved. However, heretofore no one has been able to successfully combine lightweight containers at rates greater than 700 bpm. Existing conveyor lines, and in particular discharge conveyor lines, have been designed and constructed to accommodate these production rates. However, existing conveyor lines will have difficulty in handling the greater production rates realized by this invention.
For metal type containers, such as cans, Lenhart, U.S. Pat. No. 4,669,604, teaches that if objects are first arranged in an equilateral triangle on a dead plate, the objects, such as metal cans, may be formed in a single file using a vacuum source drawn through openings in the conveyor belt to hold the outside row of containers in place on the moving belt and out of engagement with the side rails while the other containers are urged in between the containers in the outside row. However, Lenhart's invention will not work properly if the containers are delivered to it in a "random, helter-skelter fashion," or if the outermost containers on the conveyor belt are not held in a fixed position thereon, and also requires that the cans must be pushed off the dead plate by the oncoming moving mass of cans upstream of the dead plate.